Round cut gemstone

ABSTRACT

The invention provides an improved round cut gemstone, comprising a girdle, a crown above the girdle, and a pavilion below the girdle. The crown is located between the girdle and a substantially flat surface defining a table, and has two steps including a first step from the girdle to a crown break and a second step from the crown break to the table. The crown includes eight first step top corner facets, eight second step top corner facets, eight star facets, and sixteen upper girdle facets. The gemstone has a pavilion having a plurality of bottom facets and a centrally located culet at the bottom of the pavilion, and includes eight pavilion or lower corner facets, sixteen outside lower girdle facets and sixteen lower inside girdle facets.

FIELD OF THE INVENTION

This invention relates to a round cut gemstone having improved light reflecting and dispersing properties.

BACKGROUND OF THE INVENTION

Diamonds have particular characteristics that distinguish them among precious gemstones, and make them the most sought after and expensive of all gemstones. Although clear, diamonds when cut properly display brilliance and fire, owing to the reflection, dispersion, and refraction of light that impinges on their surfaces.

Brilliance includes internal brilliance, which is caused by light rays that enter the top or crown (and table if the gemstone has one), and reflect off the base or pavilion facets and back out through the top or crown undispersed.

Dispersion, also referred to as fire, occurs when white light gets broken up into its component spectral colors, in much the same way that a prism resolves light into component spectral colors. Dispersion is maximized when a ray of light is reflected totally from the base facets and strikes the crown facets at the greatest possible angle. Dispersion also occurs when a gemstone moves with respect to an observer.

Scintillation, a third characteristic, occurs when the stone, the light, or the observer moves with respect to one another. Scintillation displays itself as flashes of light, and the cut may increase or decrease the tendency of the stone to cause scintillation.

Round brilliant cut gemstones, particularly clear or uncolored diamonds, but also colored diamonds, rubies, sapphires, and emeralds tend to display more of the foregoing attributes than other cuts, and tend to show more brilliance than emerald, square, oval, and princess cuts.

The conventional round brilliant cut include 56 facets, including eight upper girdle corner facets, eight star facets, sixteen upper girdle facets, eight pavilions (or lower corner facets), and sixteen lower girdle facets. While such stones emphasize brilliance and dispersion, it would be desirable to increase these qualities, without sacrificing the overall beauty and desirability of the stone.

It is therefore an object of the present invention to provide an improved round brilliant cut that enhances the fire and brilliance of the gemstone.

SUMMARY OF THE INVENTION

This and other objects of the invention are achieved, and the disadvantages of other gemstone cuts are overcome by providing an improved round cut gemstone having an increased number of facets. In a first embodiment, the invention provides an improved round cut gemstone, comprising a girdle, a crown above the girdle, and a pavilion below the girdle, the crown located between the girdle and a substantially flat surface defining a table, the crown having two steps including a first step from the girdle to a crown break and a second step from the crown break to the table, the crown including eight first step top corner facets, eight second step top corner facets, eight star facets, and sixteen upper girdle facets. The pavilion has a plurality of bottom facets and a centrally located culet at the bottom of the pavilion. The pavilion includes eight pavilion or lower corner facets, sixteen outside lower girdle facets and sixteen lower inside girdle facets.

According to another embodiment of the invention, the invention provides an improved round cut gemstone comprising a girdle, a crown above the girdle extending to a substantially flat surface defining a table, and a pavilion below the girdle, extending from the girdle to a substantially centered culet at the bottom of the pavilion. The crown includes a first step extending from the girdle to a crown break and a second step extending from the crown break to the table. The first step has eight first step top corner facets, and eight star facets. The second step has eight second step top corner facets, sixteen upper girdle facets, and eight upper center girdle facets. The lower facets of the stone on the pavilion include eight pavilion facets, sixteen lower outside girdle facets, and sixteen lower inside girdle facets.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention will become apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiments, appended claims, and accompanying drawings in which:

FIG. 1 is a side elevational view of a first preferred embodiment of a gemstone in accordance with the present invention;

FIG. 2 is a top view of the gemstone in FIG. 1;

FIG. 3 is a bottom view of the gemstone in FIG. 1;

FIG. 4 is a side elevational view of a gemstone in accordance with another preferred embodiment of the present invention;

FIG. 5 is a top view of the gemstone of FIG. 4; and

FIG. 6 is a bottom view of the gemstone of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a first preferred embodiment of a gemstone 100 in accordance with the present invention. The gemstone 100 includes a girdle 102, a crown 104 above the girdle 102 and a pavilion 106 below the girdle 102. The pavilion 106 comes to a point at the centrally located culet 108 at the bottom thereof. The crown 104 peaks at a substantially flat table 120.

The girdle 102 extends around the perimeter of the gemstone 100 and may also be called a girdle plane. In the preferred embodiment, the girdle 102 has at least some thickness and defines some facets, but any such thickness is relatively small compared to the sizes of the facets on the crown 104 and pavilion 106. In the preferred embodiment, the girdle 102 thickness is preferably about 1-2.5% of the depth of the gemstone 100, when measured from the top surface of the table 120 to the bottom edge of the culet 108. In the preferred embodiment, the girdle thickness can be described as being “very thin” to “slightly thick,” terms known and understood to those skilled in the art.

Referring to FIG. 1, the top facets of the gemstone 100 are arrayed on the crown 104, which has two steps 110, 112. There are two crown angles a, b, which demarcate the steps of the crown 104. Angle a is the crown angle between the girdle plane and the first step 110, and angle b is the crown angle between the second step 112 and the crown break 124. In the preferred embodiment, crown angle a has a value in the range of about 34.5° to about 33°, and crown angle b has a value in the range of about 33° to about 30°. The height of each step 110, 112 in the crown 104 should preferably be approximately equal, although the upper or second step 110 can be somewhat thinner or thicker than the first or lower step 112.

The upper step 112 preferably contains sixteen facets, each substantially triangle-shaped. As shown in FIGS. 1 and 2, the facets include eight second step top corners 122, which are triangular bezels extending from the crown break 124 to table 120. The second or upper step 112 also includes eight star facets 114, which are triangular shaped facets extending from the meeting point of the corner steps to the middle of the corner of the second step 112.

The first or lower step of facets 110 preferably contains twenty-four facets, eight first step top corner facets 126, extending from the girdle 102 to the crown break 124. The first or lower step 110 also includes sixteen upper girdle facets 128, which are halves from the meeting points of the corner steps to the middle of the first step of the corner.

As shown in FIG. 2, which shows a top plan view of the crown 104, the table 120 is a flat surface at the apex of the crown 102. The table 120 is substantially octagonal, its typical shape in a round, brilliant cut stone. The table percentage, which is the width of the table 120 as a percentage of the width of the girdle 102, in the preferred embodiment is preferably in the range of about 55 to about 60%.

FIGS. 1 and 3 show the lower facets or the pavilion 106 of the gemstone 100. These include eight pavilion facets 130, which are lower corners extending from the culet 108. The lower outside girdle facets 132, which are halves from the middle of the pavilion facets on the girdle side facets to 85% to 90% of the rib of the pavilion facets toward the culet 108. The lower facets 106 also include sixteen lower inside girdle facets 134 that extend as halves from the meeting points of the lower outside girdle 102 on the girdle side facets to 30% to 40% of the rib of the outside girdle facets toward the culet 108. The gemstone 100 of FIGS. 1 and 3 thus has eighty facets, rather than the conventional fifty-six, to increase the dispersion, brilliance, and reflection of the gemstones 100, preferably a clear, colorless or colored diamond.

FIGS. 4 through 6 illustrate another preferred embodiment of the gemstone 200 of the present invention, having 88 facets. The gemstone 200 has a girdle 202, a table 220, a crown 204, containing the upper facets, and a pavilion 216, containing the lower facets. The upper facets of the stone, as can be seen with reference to FIGS. 4 and 5, include eight first step top corner facets 222 (bezels from the girdle 202 to the crown break 206) and eight second step top corner facets 224 (bezels from the crown break 206 to the table 220). The top facets also include eight star facets 226 (from the meeting point of the corner steps to the middle of the second step corner). Additionally, the crown 204 includes sixteen upper girdle facets 228 (halves from the meeting points of the corner steps to the middle of the first step of the corner), and eight upper center girdle facets 230 (facets from the girdle side).

Referring to the lower portion or pavilion side of the gemstone 200, shown in FIG. 6, the lower facets total forty in number divided as follows: eight pavilions 232 (lower corners), sixteen lower-outside girdle facets 234 (halves from the middle of the pavilions on the girdle side facets to 85-90% of the rib 238 of the pavilions toward the culet 240). The lower facets further include sixteen lower inside girdle facets 236 (halves from the middle of the lower outside girdle on the girdle side facets to 40-50% of the rib 238 of the outside girdle facets towards the culet 240).

In either embodiment, the culet 108 or 240 can be a point, a line, or a facet with some width and length. A culet range between “none” and “small,” which will be understood to those skilled in the art. “None” means that the culet has no shape, or is simply a point (or substantially a point). “Small” means that the culet, if a line, has a small length relative to the rest of the gemstone, or if a facet, has a small size relative to other facets in the gemstone.

For either embodiment of the invention, the gemstone should preferably have the following proportions:

The width of the table should preferably be about 55-60% of the overall width of the stone, the diameter at the girdle. The crown should be about 14-17% of the height of the stone, measured from the top of the table to the culet. The girdle should be 1.0% to 2.4%, while the pavilion, which extends from the lower edge of the girdle to the culet, should be about 42.5 to 44.5% of the height. The height should range from about 57.5% to 63.9% of the width.

Angle a, formed by the intersection of vertices of the upper edge of the girdle and the lower edge of the crown should range from about 33° to 34.5°. Angle b, formed at the crown break ranges from 33° to 30°.

In the preferred embodiment, the stone can be any stone, precious, semi-precious or otherwise. Examples of precious stones are diamonds, emeralds, rubies and sapphires. The gemstone of the present invention is believed to have great appeal as a diamond stone mounted to serve as a solitaire diamond engagement ring. Of course, the gemstone can be used in a wedding or other ring with other stones, or for a different article of jewelry such as for a necklace, bracelet or earring either alone or with other similar or different stones.

Although not essential to the preferred embodiment of the present invention, a diamond according to a preferred embodiment would preferably have other desirable characteristics such as color (range D-I), clarity (range internally flawless (IF)—very slightly included (VS2), carat weight, fluorescence (none-medium), polish (good-excellent) and symmetry good-excellent). These grading standards, if present in the stone, will enhance its appearance and its interaction with ambient light.

The embodiments of the present invention thus have eighty and eighty-eight facets. The facet can be made using conventional cutting techniques. A gemstone is selected for cutting after studying by the cutter and determining that it is an appropriate candidate for a round brilliant gemstone cut. For example, any significant imperfections noted in the stone must be located such that they will be cut away, or will be located in a place where they will not significantly affect the overall grade and appearance of the stone. After that, the stone is cut to provide the crown, girdle, and pavilion having the requisite number of facets for either than eighty or eighty-eight facet embodiment. Following that, the stone goes through the usual polishing and inspection steps known to those in the art.

Although two preferred embodiments have been shown and described, numerous variations and modifications will occur to those skilled in the art without departing from the spirit and scope of the invention, which is not limited to the preferred embodiments and is defined in the appended claims. 

1. An improved round cut gemstone, comprising a girdle, a crown above the girdle, and a pavilion below the girdle, the crown located between the girdle and a substantially flat surface defining a table, the crown having two steps including a first step from the girdle to a crown break and a second step from the crown break to the table, the crown including eight first step top corner facets, eight second step top corner facets, eight star facets, and sixteen upper girdle facets; the pavilion having a plurality of bottom facets and a centrally located culet at the bottom of the pavilion, the pavilion including eight pavilion or lower corner facets, sixteen outside lower girdle facets, and sixteen lower inside girdle facets.
 2. An improved round cut gemstone in accordance with claim 1, wherein the first top corner facets are bezels extending from the girdle to the crown break.
 3. An improved round cut gemstone in accordance with claim 2, wherein the second step top corners are bezels extending from the crown break to the table.
 4. An improved round cut gemstone in accordance with claim 2, wherein the star facets extend from a meeting point of two adjacent first corner steps to the middle of the second step corner.
 5. An improved round cut gemstone in accordance with claim 2, wherein the upper girdle facets are defined as halves from the meeting points of the corner steps to the middle of the first step of the corner.
 6. An improved round cut gemstone in accordance with claim 2, wherein the lower outside girdle facets are defined as halves from the middle of the pavilions on the girdle side facets to 85% to 90% of a length from the pavilion to the culet.
 7. An improved round cut gemstone in accordance with claim 2, wherein the lower girdle facets are defined as halves from a meeting point on a lower outside girdle on the girdle side facets to 30% to 40% of the rib of the outside girdle facets towards the culet.
 8. An improved gemstone in accordance with claim 2, wherein the gemstone is a diamond.
 9. An improved round cut gemstone in accordance with claim 2, wherein the gemstone has a total of 80 upper and lower facets.
 10. An improved round cut gemstone comprising a girdle, a crown above the girdle extending to a substantially flat surface defining a table, and a pavilion below the girdle, extending from the girdle to a substantially centered culet at the bottom of the pavilion, the crown including a first step extending from the girdle to a crown break and a second step extending from the crown break to the table, the first step including eight first step top corner facets, eight second step top corner facets, and eight star facets, the second step including eight second step top corner bezels, sixteen upper girdle facets, and eight upper center girdle facets, the pavilion including eight pavilion facets, sixteen lower outside girdle facets, and sixteen lower inside girdle facets.
 11. An improved round cut gemstone in accordance with claim 9, wherein the first step top corner facets are bezels extending from the girdle to the crown break.
 12. An improved round cut gemstone in accordance with claim 10, wherein the second top corner facets are bezels extending from the crown break to the table.
 13. An improved round cut gemstone in accordance with claim 10, wherein the star facets extend from a meeting point of the corner steps to the middle of the second step corner.
 14. An improved round cut gemstone in accordance with claim 10, wherein the upper center girdle facets extend from a meeting point of the corner and the upper girdle facets to about 33% to 40% of the upper girdle facets from the girdle side.
 15. An improved round cut gemstone in accordance with claim 10, wherein the upper girdle facets are halves extending from a meeting point of two corner steps to a middle first step of the corner.
 16. An improved round cut gemstone in accordance with claim 10, wherein the lower outside girdle facets include halves extending from the middle of the pavilions on the girdle side facets to 85% to 90% of a rib from the pavilions towards the culet.
 17. An improved round cut gemstone in accordance with claim 10, wherein the lower inside girdle facets are halves from the middle of the lower outside girdle on the girdle side facets to 40% to 50% of the rib from the outside girdle facets toward the culet.
 18. An improved round cut gemstone in accordance with claim 10, wherein the gemstone has 88 facets.
 19. An improved round cut gemstone in accordance with claim 17, wherein the gemstone is a diamond.
 20. A method for making an improved round cut gemstone comprising providing an uncut gemstone suitable for cutting into a round cut gemstone; cutting the gemstone to provide a round cut gemstone, comprising a girdle, a crown above the girdle, and a pavilion below the girdle, the crown located between the girdle and a substantially flat surface defining a table, the crown having two steps including a first step from the girdle to a crown break and a second step from the crown break to the table, the crown including eight first step top corner facets, eight second step top corner facets, eight star facets, and sixteen upper girdle facets, the pavilion having a plurality of bottom facets and a centrally located culet at the bottom of the pavilion, the pavilion including eight pavilion or lower corner facets, sixteen outside lower girdle facets, and sixteen lower inside girdle facets, such that the gemstone has eighty facets.
 21. A method for making an improved round cut gemstone comprising: a girdle, a crown above the girdle extending to a substantially flat surface defining a table, and a pavilion below the girdle, extending from the girdle to a substantially centered culet at the bottom of the pavilion, the crown including a first step extending from the girdle to a crown break and a second step extending from the crown break to the table, the first step including eight first step top corner facets, eight second step top corner facets, and eight star facets, the second step including eight second step top corner bezels, sixteen upper girdle facets, and eight upper center girdle facets, the pavilion including eight pavilion facets, sixteen lower outside girdle facets, and sixteen lower inside girdle facets; providing an uncut gemstone suitable for cutting into a round cut gemstone; cutting the gemstone to provide a round cut gemstone, comprising a girdle, a crown above the girdle, and a pavilion below the girdle, the crown located between the girdle and a substantially flat surface defining a table, the crown having two steps including a first step from the girdle to a crown break and a second step from the crown break to the table, the crown including eight first step top corner facets, eight second step top corner facets, eight star facets, and sixteen upper girdle facets, the pavilion having a plurality of bottom facets and a centrally located culet at the bottom of the pavilion, the pavilion including eight pavilion or lower corner facets, sixteen outside lower girdle facets, and sixteen lower inside girdle facets, such that the gemstone has eight-eight facets. 